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Hemodialysis (HD) with bicarbonate dialysis fluid (DF) requires the presence of an acid to prevent the precipitation of calcium and magnesium carbonate. The most used acid is acetic acid, with it several complications have been described. In a previous work, we described the acute changes during an HD session with a DF with citrate instead of acetate. Now, we report the results in the medium term, 16 weeks. It is a prospective, multicenter, crossover and randomized study, where 56 HD patients with bicarbonate three times a week were dialysed for 16 weeks with 3mmol/L acetate and 16 weeks with 1mmol/L citrate. Patients older than 18 years with a previous stay on HD of more than 3 months and with a normal functioning arteriovenous fistula were included. Epidemiological data, dialysis, bioimpedance, biochemistry before and after HD, as well as hypotensive episodes, were collected monthly. After 16 weeks of citrate treatment, pre-HD ionic calcium and magnesium were significantly lower and paratiroid hormone (PTH) higher than in the acetate period. No differences were observed in the effectiveness of dialysis. Hypotensive episodes were significantly more frequent with acetate than with citrate: 311 (14.1%) vs 238 (10.8%) sessions. The lean mass index increased by 0.96±2.33kg/m2 when patients switched from DF with acetate to citrate. HD with citrate modifies several parameters of bone mineral metabolism, not only acutely as previously described, but also in the long-term. The substitution of acetate for citrate improves hemodynamic stability, producing less hypotension and can improve nutritional status.

Objective: to identify possible associations between a higher probability of falls among hemodialysis patients and laboratory values, comorbidities, pharmacological treatment, hemodynamic changes, dialysis results and stabilometric alterations. Method: this was a retrospective case-control study with hemodialysis patients. Patients in a hemodialysis unit who had suffered one or more falls were included in the case group. Patients from the same unit who had not suffered falls were the controls. Data were gathered from the patients’ clinical history and also from the results of a balance test conducted six months before the study. Results: thirty-one patients were included (10 cases and 21 controls). Intradialytic body weight change was significantly greater among cases (p

En este trabajo se presenta una aplicación y comprobación del método de jerarquías analíticas (AHP, por sus siglas en inglés) a la toma de decisiones respecto a la gestión de fugas que llevará a cabo una empresa de suministro de agua potable. En la evaluación de alternativas serán considerados no solo los costos del desarrollo del proyecto, sino también algunas externalidades sociales y ambientales, con la finalidad de que la decisión tomada se ajuste más a la realidad de la empresa y su entorno. Para la correcta aplicación de AHP y para la validación de los resultados obtenidos, se hace hincapié en los requisitos que se deben cumplir en la construcción de matrices de comparación para ser consideradas válidas. Estas características son: positividad de sus componentes, homogeneidad, reciprocidad y consistencia, presentando esta última considerable complejidad, lo que ha motivado la generación de opciones para su mejora.

La curva de consigna es una herramienta bastante utilizada en la optimización energética de los sistemas de agua potable que trabajan por bombeo. En el presente trabajo se analizan otras aplicaciones como la esqueletización, la sectorización, la determinación de la capacidad de la red y los procesos de incremento de la demanda debido al crecimiento urbano horizontal y/o vertical. Asimismo, se estudian sus características cuando existe la presencia de fugas, cambios de la presión mínima y cambios en la rugosidad de la red. Estas propiedades y aplicaciones potenciales convierten a la curva de consigna en una herramienta muy útil para la planificación, diseño, gestión y mantenimiento de las redes de suministro de agua.

Water Supply Network (WSN) sectorization is a broadly known technique aimed at enhancing water supply management. In general, existing methodologies for sectorization of WSNs are limited to assessment of the impact of its implementation over reduction of background leakage, underestimating increased capacity to detect new leakage events and undermining appropriate investment substantiation. In this work, we raise this issue and put in place a methodology to optimize sectors' design. To this end, we carry out a novel combination of the Short Run Economic Leakage Level concept (SRELL- corresponding to leakage level that can occur in a WSN in a certain period of time and whose reparation would be more costly than the benefits that can be obtained). With a non-deterministic optimization method based on Genetic Algorithms (GAs) in combination with Monte Carlo simulation. As an example of application, methodology is implemented over a 246 km pipe-long WSN, reporting 72 397 $/year as net profit.

La importancia de la previsión de la demanda de agua aumenta con la complejidad de los sistemas de abastecimiento de agua. Muchos métodos de predicción de demanda de agua, básicamente fundados en el análisis de series temporales y en mecanismos de regresión basados en métodos de aprendizaje automático, han sido propuestos en la literatura. Los últimos necesitan de un estudio detallado de las variables involucradas y de la elección de la mejor arquitectura para la producción de resultados relevantes. Ese trabajo propone como alternativa aplicar dos métodos conocidos de aproximación de datos, a saber, las series discretas de Fourier y los polinomios de Chebyshev, a la previsión de demanda en tiempo real con actualización instantánea de los coeficientes ajustables en cada una de las funciones. Para contrastar la metodología propuesta se analizó un sector de una red real de abastecimiento de agua. Los resultados obtenidos muestran una buena aproximación entre los valores medidos y los predichos. El punto más interesante de la aplicación es la agilidad de cálculo y el hecho de que no hay necesidad de tener información de los factores que influyen en la demanda de agua.

[EN] The most important factor in planning and operating water distribution systems is satisfying consumer demand. This means continuously providing users with quality water in adequate volumes at reasonable pressure, thus ensuring reliable water distribution. In recent years, the application of statistical, machine learning, and artificial intelligence methodologies has been fostered for water demand forecasting. However, there is still room for improvement; and new challenges regarding on-line predictive models for water demand have appeared. This work proposes applying support vector regression, as one of the currently better machine learning options for short-term water demand forecasting, to build a base prediction. On this model, a Fourier time series process is built to improve the base prediction. This addition produces a tool able to eliminate many of the errors and much of the bias inherent in a fixed regression structure when responding to new incoming time series data. The final hybrid process is validated using demand data from a water utility in Franca, Brazil. Our model, being a near real-time model for water demand, may be directly exploited in water management decision-making processes. (C) 2016 Elsevier B.V. All rights reserved., This work has been partially supported by CAPES Foundation of Brazil’s Ministry of Education. The data were provided by SABESP, São Paulo state water management company.

The addition of phosphorus (P) to the dialysate (LD) in the form of enema Casen® is common practice in patients with hypophosphatemia. The estimation of the amount to be used and the identification of the problems that may can occur are not well defined. As a result of our work we propose a practical approach of how to proceed to increase phosphate concentration in the hemodialysate. We present a reasoned formula to calculate how much enema has to be added and the problems that may arise.

Introduction: Postural balance is the result of a complex interaction of sensory input which keeps us upright. Haemodialysis patients have alterations which can lead to postural instability and a risk of falls. Our objective was to analyse postural stability and its relationship with the risk of falls in haemodialysis patients using a force platform. Material and methods: This was a prospective cross-sectional study. Postural balance was recorded using a force platform in prevalent haemodialysis patients. We collected epidemiological, dialysis, analytical and treatment data. The incidence of falls was recorded over the six months following the tests. The postural stability analysis was performed with a portable strain gauge platform (AMTI AccuGait®) and a specific software unit for stabilometry (Balance Trainer® program). We measured 31 balance parameters; the balance variables used were: Area95; Area effect; VyMax; Xrange and Yrange. The stabilometry studies were performed in three situations: with eyes open (EO); with eyes closed (EC); and with the patient performing a simultaneous task (COG). We performed one study at the start of the dialysis session, and a second study at the end. Stabilometry was measured in a control group under similar conditions. Results: We studied 32 patients with a mean age of 68 years old; of this group, 20 subjects were male and 12 were female. Their mean weight was 74 kg, with a mean BMI of 27.6 kg/m2. In the controls, there were no significant differences in the stabilometry between the three situations studied. Both pre- and post-haemodialysis, patients with closed eyes showed greater imbalance, and there were significant differences with the other situations and controls. We found a significant increase in instability after the haemodialysis session, and greater instability in the 13 patients with diabetes (p

ResumenIntroducciónAl igual que en la población general, en los pacientes en hemodiálisis (HD), la hiponatremia también se asocia a mayor riesgo de muerte. El objetivo de este trabajo es estudiar en la población en HD la relación entre natremia y mortalidad. Definir hiponatremia en HD y determinar qué peculiaridades tienen los pacientes hiponatrémicos en relación con aspectos antropométricos, analíticos, dialíticos y de hidratación, mediante bioimpedancia.MetodosEstudio observacional, descriptivo, de una cohorte de pacientes incidentes en HD. La variable independiente fue la media de las natremias medidas en los 6 primeros meses en HD.ResultadosSe incluyó a 4.153 pacientes. La edad media era de 64,7 años y predominaban los hombres con un 64,2%. Un 34,8% eran diabéticos. El tiempo medio de seguimiento fue 21,48 (DE) (1,31) meses. Las natremias tenían una distribución normal, con una media (DE) de 138,46 (2,7) mEq/l. Las variables que presentan diferencias significativas en función de los cuartiles de natremia son: peso, diabetes, presión arterial sistólica, ganancia de peso interdialítica, ultrafiltración total, glucemia, albúmina y creatinina séricas y tipo de acceso vascular y de HD.El índice de masa magra (LTI) en los pacientes con hiponatremia, Q1 (135 mEq/l), fue significativamente más bajo que el del resto de pacientes. Los pacientes con una natremia menor de 136 mEq/l tienen un riesgo independiente de mortalidad mayor que el resto (OR=1,62) (análisis de regresión de Cox).ConclusionesLos pacientes en HD con hiponatremia tienen mal pronóstico y presentan desnutrición o sobrecarga de volumen.AbstractBackgroundAs in the general population, in patients on haemodialysis (HD) hyponatraemia is associated with higher mortality risk. The objective of this article was to study the relationship between predialysis serum sodium (sNa) and mortality in an HD population. We also intended to define hyponatraemia and determine the characteristics of hyponatraemic patients in terms of anthropometric data, analytical features, dialysis measurements and hydration (bioimpedance).MethodsObservational, descriptive study of a cohort of HD incident patients. The independent variable was the mean of each patient's sNa analysed during their first 6 months on HD.ResultsA total of 4,153 patients were included in the study. Mean age was 64.7 years; 65.2% of the patients were male and 35% were diabetics. Mean follow-up time was 21.48 (SD) (1.31) months. sNa had a normal distribution, with a mean (SD)=138.46 (2.7) mEq/l. Body weight, diabetes mellitus, systolic blood pressure, interdialytic weight gain, total ultrafiltration, serum glucose, albumin and creatinine, vascular access and haemodialysis type, acquire significant differences between sodium quartiles. Lean tissue index (LTI) in patients with low serum sodium, Q1 (135 mEq/l), was significantly lower than the LTI of patients from the other serum sodium quartiles. Patients with sNa

Decision making (DM) processes are becoming increasingly complex. The reasons are manifold. DM usually involves many aspects; some are purely technical, while others are subjective and derived from social, political, and environmental factors, among others. As a result, they involve items that are not easily comparable under the same units of measurement. Problems are made even more complex by the fact that current governance processes tend to involve all the stakeholders in the DM process. In this paper we consider the AHP methodology (analytic hierarchy process), which is used to build consistent aggregate results from data provided by decision makers. As some of the actors involved may not be completely familiar with all the criteria under consideration, it is common that the body of opinion, expressed in terms of pairwise comparison, is incomplete. To overcome this weakness, we propose a framework that enables users to provide data on their preferences in a partial and/or incomplete way and at different times. This article is an advance towards a dynamic model of AHP. The authors have addressed the problem of adding a new criterion or deleting obsolete criteria. Here, we address the consistent completion of a reciprocal matrix as a mechanism to obtain a consistent body of opinion issued in an incomplete manner by a specific actor. This feature is incorporated into a process of linearization previously introduced by the authors, which is concisely presented. Finally, we provide an application for leakage control in a water supply company. The adoption of suitable control leakage policies in water supply is a problem of enormous interest in the water industry, particularly in urban hydraulics., This work has been funded as part of project IDAWAS, DPI2009-11591 by the Direccion General de Investigacion del Ministerio de Ciencia e Innovacion (Spain); with supplementary support from ACOMP/2011/188 from the Conselleria d'Educacio of the Generalitat Valenciana. The first author also received support from Spanish project PAID-06-12. The use of English in this paper was revised by John Rawlins.

Backgrounds and purposes: Patients with chronic kidney disease (CKD) have higher risk of developing cardiovascular disease. In CKD patients the mechanisms involved in, endothelial damage and the role of different drugs used on these patients are not completely understood. The aim of this work is to analyze the effect of statins and platelet antiaggregant (PA) on endothelial microvesicles (EMVs) and other markers of endothelial dysfunction. Experimental approach: Cross-sectional study of 41 patients with CKD 3b-4 and 8 healthy volunteers. Circulating levels of EMVs, vascular endothelial growth factor (VEGF), and advance oxidized protein products (AOPPS) were quantified and the correlation with different comorbidity variables and therapeutic strategies were evaluated. Results: EMVs are increased in CKD patients as compared with controls (171.1 vs. 68.3/μl, p

This paper presents some aspects of the time propagation of underground water leakage in controlled laboratory conditions using a drilled polyvinyl chloride (PVC) pipe and interpreting ground penetrating radar (GPR) images. GPR pre-processed images are interpreted for easy identification and extraction of surfaces and volumes of water leakage. Finally, the temporal evolution of a water leak is shown using 3D models based on interpretation of GPR images. Water volumes obtained using this approach can be easily observed by personnel who lack highly specialized training in the analysis of raw data. The results of this study are promising and can help develop techniques to validate non-destructive models for the identification, distribution, and prediction of water leaks in water supply systems using GPR., Part of this work has been developed under the support of an FPI (Formacion de Personal Investigador)-UPV (Universitat Politecnica de Valencia) scholarship granted to the second author by the Programa de Ayudas de Investigacion y Desarrollo (PAID) of the Universitat Politecnica de Valencia, and the support of Fundacion Carolina PhD, within its short stances scholarship program for the first author. The use of English in this paper has been revised by John Rawlins.

Purpose The biocompatibility of dialyzers may influence the inflammatory state of hemodialysis patients. This study compares the effect of a high-flux polynephron membrane with other high-flux membranes, helixone and polyamide, on some inflammation biomarkers based on the analysis of circulating mononuclear cells (MC). Methods The study included 47 patients on hemodialysis with helixone and polyamide; 9 formed the control group, without changes in their dialyzers throughout the study, and 38 formed the intervention group, in which their dialyzers were replaced by polynephron. In both groups, blood samples were taken at the beginning of the study before and after hemodialysis session, and at the end of the study 4 months later. In each extraction, biochemical parameters were determined, and MC isolated using Ficoll gradient. Production of reactive oxygen species and the percentage of activated MC (CD14+CD16+) were measured by flow cytometry, and protein levels of heat-shock proteins (Hsp70/Hsp90) studied by Western blot. Results After 1 hemodialysis session with different membranes, no significant differences were observed in the different parameters considered. After 4 months of dialysis with polynephron, a significant reduction in the percentage of CD14+CD16+ and in the β2-microglobulin reduction ratio were found, with respect to helixone and polyamide, without changes in the other parameters analyzed. Conclusions The use of polynephron for 4 months reduces the percentage of CD14+CD16+ compared to helixone and polyamide, suggesting a better profile regarding activation of the inflammatory response. These findings could be explained by a better biocompatibility or an increased reduction of medium-sized toxic molecules.

Background: The majority of studies suggesting that online hemodiafiltration reduces the risk of mortality compared to hemodialysis (HD) have been performed in dialysis-prevalent populations. In this report, we conducted an epidemiologic study of mortality in incident dialysis patients, comparing post-dilution online hemodiafiltration and high-flux HD, with propensity score matching (PSM) used to correct indication bias. Methods: Our study cohort comprised 3,075 incident dialysis patients treated in 64 Spanish Fresenius Medical Care clinics between January 2009 and December 2012. The primary outcome of this study was to investigate the impact of the type of renal replacement on all-cause mortality. An analysis of cardiovascular mortality was defined as the secondary outcome. To achieve these objectives, patients were followed until December 2016. Patients were categorized as high-flux HD patients if they underwent this treatment exclusively. If >90% of their treatment was with online hemodiafiltration, then the patient was grouped to that modality. Results: After PSM, a total of 1,012 patients were matched. Compared with patients on high-flux HD, those on online hemodiafiltration received a median replacement volume of 23.45 (interquartile range 21.27–25.51) L/session and manifested 24 and 33% reductions in all-cause and cardiovascular mortality (all-cause mortality hazards ratio [HR] 0.76, 95% CI 0.62–0.94 [p = 0.01]; and cardiovascular mortality HR 0.67, 95% CI 0.50–0.90 [p = 0.008]). Conclusions: This study shows that post-dilution online hemodiafiltration reduces all-cause and cardiovascular mortality compared to high-flux HD in an incident HD population.

[EN] One of the problems for water supply systems with intermittent supply is the peak flow produced at some hours of the day, which is usually much larger than that in a system with continuous supply. The main consequence is the reduction of pressure and flow at the ends or highest points of the system network. This, in turn, generates inequity in water supply and complaints from users. To reduce the peak flow, some sectors of the system must be assigned a different supply schedule. As a result, the supply curve is modified, and the peak flow is reduced. This reorganization seeks some optimal allocation schedule and must be based on various quantitative and qualitative technical criteria. This paper hybridizes integer linear programming and multi-criteria analysis to contribute with a solution proposal to the technical management of intermittent water supply systems, which provides short-term results and requires little investment for implementation. This solution does not seek perpetuating intermittent water supply. On the contrary, this methodology can be a useful tool in gradual transition processes from intermittent to continuous supply. (C) 2016 Elsevier B.V. All rights reserved.

[EN] Hybrid models have been used in many engineering applications in order to find better solutions and to reduce project costs. In this paper a methodology for the optimal design of collective working shift irrigation systems is proposed. The proposal is based on a hybrid model of optimization, which includes Linear Programming (LP) and Genetic Algorithms (GA). The method is applied to an irrigation network to check its effectiveness to minimize the total investment costs for pipelines. The results are compared to another hybrid model for optimization, which is based on Nonlinear Programming (NLP) and GA. The advantage of the developed method is a more cost effective design using discrete pipeline diameters. (C) 2016 Published by Elsevier Ltd., Thanks to the Technical University of Loja/Ecuador for funding the research, the Gestar group of investigation of the University of Zaragoza, Spain and to Dr. Andreas Fries.

[EN] This work focuses on the use of easy-to-apply procedures that allow rapid visualization of components of water supply systems (WSSs) by non-highly qualified personnel. We use a methodology that does not alter the conditions and characteristics of the environment (nondestructive methods), specifically the study of images obtained with ground penetrating radar (GPR). The study is based on the analysis and interpretation of the wave amplitude, then applying a series of image corrections, so that the display and handling of data is improved. The results are promising as a subjective and repeatable methodology to visualize buried pipes efficiently. The goal is to generate know-how to be able to train intelligent systems for the characterization of components of WSSs, Part of this work has been developed under the support of an FPI (Formación de Personal Investigador)-UPV (Universitat Politècnica de València) scholarship granted to the first author by the Programa de Ayudas de Investigación y Desarrollo (PAID) of the Universitat Politècnica de València.

Optimal design of water distribution systems (WDSs), including the sizing of components, quality control, reliability, renewal, and rehabilitation strategies, etc., is a complex problem in water engineering that requires robust methods of optimization. Classical methods of optimization are not well suited for analyzing highly dimensional, multimodal, nonlinear problems, especially given inaccurate, noisy, discrete, and complex data. Agent Swarm Optimization (ASO) is a novel paradigm that exploits swarm intelligence and borrows some ideas from multiagent-based systems. It is aimed at supporting decision-making processes by solving multiobjective optimization problems. ASO offers robustness through a framework where various population-based algorithms coexist. The ASO framework is described and used to solve the optimal design of WDS. The approach allows engineers to work in parallel with the computational algorithms to force the recruitment of new searching elements, thus contributing to the solution process with expert-based proposals. © 2014 Computer-Aided Civil and Infrastructure Engineering.

Sectorization is a process aimed at efficiently managing Water Supply Networks (WSNs). There are many large WSNs where the number of sectors into which they might be subdivided is initially unknown. Our method uses concepts derived from the Social Network Theory (SNT) such as centrality and community detection to obtain such subdivisions. The output is then evaluated through energy criteria. This methodology entails two very important benefits over other methods previously proposed. Firstly, it is applicable to WSNs depending on a network trunk and, secondly, it considers the technical know-how of the staff of the water utility.

[EN] This document shows some aspects regarding water leakage time propagation through the underground, in controlled laboratory conditions, using a drilled PVC pipe, through the interpretation of GPR images. The extraction of relevant patterns is possible since GPR interpretations allow to obtain surfaces and volumes that can be easily identified by non-highly specialized personnel in the analysis of raw data. The results of this study are promising since they help promote the realization of techniques able to validate models for generation, distribution and prediction of water leaks in water supply systems using GPR as a non-destructive method., Part of this work has been developed under the support of an FPI (Formación de Personal Investigador)- UPV (Universitat Politècnica de València) scholarship granted to the first author by the Programa de Ayudas de Investigación y Desarrollo (PAID) of the Universitat Politècnica de València

The evolution of technologies of informatics and telecommunications has improved significantly the way water distribution systems can be managed. The use of quasi real-time information is becoming a desired standard in many water utilities. Nevertheless, tools for water distribution system analysis and for supporting decision making haveńt been integrated with the same speed. This research uses cloud computing capabilities for supporting analysis and decision making in water distribution systems. It includes the development of evolutionary algorithms ready to run in a cloud environment for searching the best possible decisions considering a set of objectives. The evaluation of solutions profits from the scalability of the cloud for making faster the solution search process.

Knowledge of buried infrastructure is essential for management and decision-making in water utility companies. To pinpoint the benefits of thermography, a case study was conducted, namely, thermal images were taken under various conditions in a particular area containing a buried pipe. Thermal images were subsequently analysed, an image database supplemented with environmental data generated, and a data mining method applied. The results generated this way complement the raw images and reveal additional relationships regarding the visibility of the infrastructure, and the possibility of making promising improvements in infrastructure identification, which can be applied in subsequent work in other applications.

This paper addresses the problem of leakage in water distribution systems through the use of ground penetrating radar (GPR) as a nondestructive method. Laboratory tests are performed to extract features of water leakage from the obtained GPR images. Moreover, a test in a real-world urban system under real conditions is performed. Feature extraction is performed by interpreting GPR images with the support of a pre-processing methodology based on an appropriate combination of statistical methods and multi-agent systems. The results of these tests are presented, interpreted, analyzed and discussed in this paper. © 2013 by the authors; licensee MDPI, Basel, Switzerland., SCOPUS: ar.j, info:eu-repo/semantics/published

This paper uses a multi-agent approach as a quick and easy tool for the interpretation and analysis of the characteristics of Water Supply System (WSS) components when working on a collection of Ground Penetrating Radar (GPR) survey files. The multi-agent algorithm proposed in this paper has been developed in Matlab and is based on Game Theory. The input is the result of the GPR radargram survey and the output consists of the agent scores in the game proposed in this paper. Useful information can be gained by interpreting the columns of the output matrix that describe the agents’ movements, together with the associated racing times. In effect, this analysis enables a simple determination of the electromagnetic properties of the underground system and provides an accurate classification of these properties. The results of this agent racing algorithm are promising, since it groups, and consequently, decreases the number of points that make up the initial radargrams; while at the same time preserving its main properties, and enabling clearer views of pipes and a better identification of the components in WSS., This work has been supported by project IDAWAS, DPI2009-11591, of the Direccion General de Investigacion of the Ministerio de Ciencia e Innovacion of Spain, ACOMP/2011/188 of the Conselleria de Educacion of the Generalitat Valenciana, and the FPI-UPV scholarship granted to the first author by the Programa de Ayudas de Investigacion y Desarrollo (PAID) of the Universitat Politecnica de Valencia.

[EN] We introduce a methodology based on spectral measurements of graph theory to establish the relative importance of areas in water supply networks (WSNs). To achieve an efficient vulnerability analysis, we have made a prospective study to establish the importance of areas based on two popular ranking algorithms - PageRank and HITS. These areas are analysed using a flexible method of semi-supervised clustering. This approach enables better control because it works top-down from the whole network to the detail of a particular area; and provides valuable additional support for assessing vulnerability in WSNs. (C) 2011 Elsevier Ltd. All rights reserved., This work has been supported by the project IDAWAS, DPI2009-11591, of the Direccion General de Investigacion of the Ministerio de Ciencia e Innovacion of Spain and the complementary support ACOMP/2011/188, of the Conselleria de Educacio of the Generalitat Valenciana.

Computational modeling pervades virtually every industrial process. By using numerical representations of the behavior of elements that constitute a system it is possible to obtain efficient and safe designs. Moreover, system operation can be better defined by using such models, thus enabling greater reliability and control. In this paper the use of agents to solve the equations describing fast transients in water networks is investigated. As the simulation of hydraulic transients in pressurized systems is a naturally distributed problem, the authors argue that a multi-agent based system is very suitable for the solution of this complex engineering phenomenon. A hybrid solution is built by deploying agents to work with sets of equations describing hydraulic transient behavior in pipeline systems. The details necessary to assemble a complete and lubricated machine to model the complex phenomenon of hydraulic transients in pressurized systems are described. This research develops a platform that constitutes an efficient and versatile tool of great interest for water supply managers when analyzing water hammer effects in their networks.

The core idea behind sectorization of Water Supply Networks (WSNs) is to establish areas partially isolated from the rest of the network to improve operational control. Besides the benefits associated with sectorization, some drawbacks must be taken into consideration by water operators: the economic investment associated with both boundary valves and flowmeters and the reduction of both pressure and system resilience. The target of sectorization is to properly balance these negative and positive aspects. Sectorization methodologies addressing the economic aspects mainly consider costs of valves and flowmeters and of energy, and the benefits in terms of water saving linked to pressure reduction. However, sectorization entails other benefits, such as the reduction of domestic consumption, the reduction of burst frequency and the enhanced capacity to detect and intervene over future leakage events. We implement a development proposed by the International Water Association (IWA) to estimate the aforementioned benefits. Such a development is integrated in a novel sectorization methodology based on a social network community detection algorithm, combined with a genetic algorithm optimization method and Monte Carlo simulation. The methodology is implemented over a fraction of the WSN of Managua city, capital of Nicaragua, generating a net benefit of 25,572 $/year.

[EN] Water supply systems have been facing many challenges in recent decades due to the potential effects of climate change and rapid population growth. Water systems need to expand because of demographic growth. Therefore, evaluating and increasing system capacity is crucial. Specifically, we analyze network capacity as one of the main features of a system. When the network capacity starts to decrease, there is a risk that continuous supply will become intermittent. This paper discusses how network expansion carried out throughout the network life span typically reduces network capacity, thus transforming a system originally designed to work with continuous supply into a system with intermittent supply. A method is proposed to expand the network capacity in an environment of economic scarcity through a greedy algorithm that enables the definition of a schedule for pipe modification stages, and thus efficiently expands the network capacity. This method is, at the same time, an important step in the process of changing a water system from intermittent back to continuous supply an achievement that remains one of the main challenges related to water and health in developing countries.

A novel methodology to sectorize water supply networks (WSNs) depending on a main transmission line is presented in this paper. The methodology is based on concepts derived from the social network theory and graph theory (namely, community detection and shortest path respectively); and also on a multi-objective optimization process by means of agent swarm optimization (ASO). A series of energy, operative, and economic criteria are optimized in this process. The core idea is to form sectors over the distribution network based on communities found using a community detection algorithm (Walktrap). The methodology is flexible and enables the technical staff in water utilities to make decisions at different stages. It has been tested by generating four feasible solutions over a portion of a real WSN.

Decision making in engineering is becoming increasingly complex due to the large number of alternatives and multiple conflicting goals. Powerful decision-support expert systems powered by suitable software are increasingly necessary. In this paper, the multiple attribute decision method known as analytical hierarchy process (AHP), which uses pairwise comparisons with numerical judgments, is considered. Since judgments may lack a minimum level of consistency, mechanisms to improve consistency are necessary. A method to achieve consistency through optimisation is described in this paper. This method has the major advantage of depending on just n decision variables – the number of compared elements – and so is less computationally expensive than other optimisation methods, and can be easily implemented in virtually any existing computer environment. The proposed approach is exemplified by considering a simplified version of one of the most important problems faced by water supply managers, namely, the minimisation of water loss. 2012 Elsevier Inc. All rights reserved., This work has been performed under the support of project IDAWAS, DPI2009-11591 of the Direccionn General de Investigacion del Ministerio de Educacion y Ciencia (Spain) and ACOMP/2011/188 of the Conselleria de Educacion de la Generalitat Valenciana. The first author was supported by Spanish project MTM2010-18539. The third author is also indebted to the Universitat Politecnica de Valencia for the sabbatical leave granted during the first semester of 2011. The use of English in this paper was revised by John Rawlins.

This article introduces some approaches to common issues arising in real cases of water demand prediction. Occurrences of negative data gathered by the network metering system and demand changes due to closure of valves or changes in consumer behavior are considered. Artificial neural networks (ANNs) have a principal role modeling both circumstances. First, we propose the use of ANNs as a tool to reconstruct any anomalous time series information. Next, we use what we call interrupted neural networks (I-NN) as an alternative to more classical intervention ARIMA models. Besides, the use of hybrid models that combine not only the modeling ability of ARIMA to cope with the time series linear part, but also to explain nonlinearities found in their residuals, is proposed. These models have shown promising results when tested on a real database and represent a boost to the use and the applicability of ANNs., This work has been supported by project IDAWAS, DPI2009-11591, of the Direccion General de Investigacion of the Ministerio de Ciencia e Innovacion of Spain, and ACOMP/2010/146 of the Conselleria de Educacion of the Generalitat Valenciana. As well, the authors are grateful to "Aguas de Murcia" for the collaboration in this work and for the availability of the data., This work has been supported by project IDAWAS, DPI2009-11591, of the Direccion General de Investigacion of the Ministerio de Ciencia e Innovacion of Spain, and ACOMP/2010/146 of the Conseller a de Educacion of the Generalitat Valenciana. As well, the authors are grateful to "Aguas de Murcia" for the collaboration in this work and for the availability of the data.

One of the main challenges that water supply managers face is that of minimizing the water lost through leakage from the systems that they operate. To minimize water losses, substantial amounts of money must be invested every year in leak detection and repairs. This investment is usually balanced by the benefits derived from the use of the recovered water. Nevertheless, this scheme of economic assessment does not reflect the whole dimension of the profit-earning capacity of repairing leaks; and the associated benefits go beyond just the economic value of the recovered water. In this paper, we consider a new economic assessment approach that includes all the costs incurred by the existence of leaks and the benefits derived from their control. The main difficulty derives from the fact that comparisons with regard to certain properties will only work for properties with well-defined scales of measurement. The analytic hierarchy process of Saaty (2008) [1] provides a useful way to establish relative scales that are derived by making pairwise comparisons using numerical judgments from an absolute scale of numbers. The unique largest eigenvalue and the Perron eigenvector of the matrix of criteria provide, taking into account the properties that this matrix exhibits, the necessary information for dealing with complex decisions that involve dependence and feedback. These decisions are analyzed in the context of benefits, opportunities, costs, and risks. We also present a method for improving the consistency of the comparisons - as consistency may be affected by subjectivity. The main conclusion is that water supply managers and authorities should shift direction from purely economic policies based on passive leakage control towards new social and environmental policies that consider more proactive actions.

The work presented in the paper intends to solve the problem of analyzing a looped network taking into account the expected peak flows in the links. Usually, models are based on averaged demands based on the customers’ billings. In some cases, demands are corrected with global peak coefficients. The writers propose a new approach for analyzing water supply networks under peak demand situations. This method is based on individual peak coefficients for each link. After that, a new method for demand load allocation is described in order to satisfy the continuity equation in nodes. The procedure is iterative and was implemented using the hydraulic solver used by EPANET. Two case studies complete the paper. The first case study consists of a very simple network and allows one to describe the method. The second one is a small, real network and demonstrates the applicability to bigger networks.

Selecting the most appropriate heuristic for solving a specific problem is not easy, for many reasons. This article focuses on one of these reasons: traditionally, the solution search process has operated in a given manner regardless of the specific problem being solved, and the process has been the same regardless of the size, complexity and domain of the problem. To cope with this situation, search processes should mould the search into areas of the search space that are meaningful for the problem. This article builds on previous work in the development of a multi-agent paradigm using techniques derived from knowledge discovery (data-mining techniques) on databases of so-far visited solutions. The aim is to improve the search mechanisms, increase computational efficiency and use rules to enrich the formulation of optimization problems, while reducing the search space and catering to realistic problems.

Background Increasing dialysate flow rates (Qd) from 500 to 800 ml/min has been recommended to increase dialysis efficiency. A few publications show that increasing Qd no longer led to an increase in mass transfer area coefficient (KoA) or Kt/V measurement. Our objectives were: 1) Studying the effect in Kt of using a Qd of 400, 500, 700 ml/min and autoflow (AF) with different modern dialysers. 2) Comparing the effect on Kt of water consumption vs. dialysis time to obtain an individual objective of Kt (Ktobj) adjusted to body surface. Methods This is a prospective single-centre study with crossover design. Thirty-one patients were studied and six sessions with each Qd were performed. HD parameters were acquired directly from the monitor display: effective blood flow rate (Qbe), Qd, effective dialysis time (Te) and measured by conductivity monitoring, final Kt. Results We studied a total of 637 sessions: 178 with 500 ml/min, 173 with 700 ml/min, 160 with AF and 126 with 400 ml/min. Kt rose a 4% comparing 400 with 500 ml/min, and 3% comparing 500 with 700 ml/min. Ktobj was reached in 82.4, 88.2, 88.2 and 94.1% of patients with 400, AF, 500 and 700 ml/min, respectively. We did not find statistical differences between dialysers. The difference between programmed time and Te was 8′ when Qd was 400 and 500 ml/min and 8.8′ with Qd = 700 ml/min. Calculating an average time loss of eight minutes/session, we can say that a patient loses 24′ weekly, 312′ monthly and 62.4 hours yearly. Identical Kt could be obtained with Qd of 400 and 500 ml/min, increasing dialysis time 9.1′ and saving 20% of dialysate. Conclusions Our data suggest that increasing Qd over 400 ml/min for these dialysers offers a limited benefit. Increasing time is a better alternative with demonstrated benefits to the patient and also less water consumption. Electronic supplementary material The online version of this article (doi:10.1186/s12882-015-0013-9) contains supplementary material, which is available to authorized users.

In many real-world applications we have at our disposal a limited number of inputs in a theoretical database with full information, and another part of experimental data with incomplete knowledge for some of their features. These are cases that can be addressed by a label propagation process. It is a widely studied approach that may acquire complexity if new constraints in the new unlabeled data that should be taken into account are found. This is the case of the membership to a group or community in graphs. The proposal is to add the Laplacian matrix as well as another different similarity measures (may be not found in the original database) in the label propagation. A kernel embedding process together with a simple label propagation algorithm will be the main tools to achieve this approach by the use of all types of available information. In order to test the functionality of this new proposal, this work introduces an experimental study of biofilm development in drinking water pipes. Then, a label propagation through pipes belonging to a complete water supply network is approached. These pipes have their own properties depending on their network location and environmental co-variables. As a result, the proposal is a suitable and efficient way to deal with practical data, based on previous theoretical studies by the constrained label propagation process introduced.

Despite the well known association between interleukin-6 (IL-6) and cardiovascular mortality, no study has so far verified whether IL-6 adds prognostic information to that provided by C-reactive protein (CRP).A cohort of 218 haemodialysis patients from four different dialytic centres was followed-up retrospectively. Plasma IL-6 and CRP concentrations were determined. Full information on co-morbidities was available in 162 patients.With respect to the lowest quartile (3.6 pg/ml for IL-6, and2.2 mg/l for CRP), the crude relative risk (RR) of death from all causes of the upper quartile (13.9 pg/ml for IL-6, and12.8 mg/l for CRP) was 5.20 (95% confidence interval 2.06-13.011) for IL-6 and 3.16 (1.41-7.12) for CRP. When both variables were included, the estimates were 4.10 (1.30-12.96) for IL-6 and 1.29 (0.47-3.57) for CRP. As to continuous variables, the relationship between both variables and mortality tended to level off for the highest values, but became fairly linear after log transformation of the variables. For one unit SD of the log (variable), the RR was 2.09 (1.52-2.88) for IL-6 and 1.66 (1.23-2.24) for CRP. When they were included in the same model, the estimates were 1.90 (1.18-2.82) for IL-6 and 1.16 (0.81-1.66) for CRP.IL-6 has a stronger predictive value than CRP for cardiovascular mortality and provides independent prognostic information, while conveying most of that provided by CRP.

AM3 (Inmunoferon®) as an adjuvant to hepatitis B vaccination in hemodialysis patients. Background Patients with end-stage renal disease (ESRD) undergoing hemodialysis have severe alterations in cell-mediated immunity (CMI) that increases their risk of contracting chronic hepatitis B virus (HBV) infection and decreases their protective responses to HBV vaccine. In an effort to improve the humoral response to an accelerated HBV vaccine protocol in these patients, the ability of an immunomodulator, AM3, to improve seroconversion was investigated. Methods A total of 269 patients were enrolled in a multicenter trial. All patients received a DNA recombinant vaccine (40 μg HBsAg/dose/day) on days 0, 10, 21, and 90. AM3 or placebo (3 g/day) was given orally for 30 consecutive days beginning 15 days prior to the first vaccine dose. Anti-HBsAg titers were measured on days 120 and 270 after the beginning of the trial. Results After one month, 207 patients could be evaluated and 132 patients after six months. The placebo and AM3-treated groups had comparable seroconversion and protective response rates one month after the final vaccine dose. The AM3 treatment group, but not the placebo group, maintained these protective titers up to six months after the final vaccine dose. At this time, the percentage of high responders (anti-HBsAg>100 IU/L) and mean anti-HBsAg titers in the AM3 group was significantly higher than in the placebo group. Conclusions AM3 is a safe and easily tolerated oral agent that potentiates long-term serological immunity to hepatitis B in hemodialysis patients after vaccination.

Optimizing anemia treatment in hemodialysis (HD) patients remains a priority worldwide as it has significant health and financial implications. Our aim was to evaluate in a large cohort of chronic HD patients in Fresenius Medical Care centers in Spain the value of cumulative iron (Fe) dose monitoring for the management of iron therapy in erythropoiesis-stimulating agent (ESA)-treated patients, and the relationship between cumulative iron dose and risk of hospitalization. Demographic, clinical and laboratory parameters from EuCliD® (European Clinical Dialysis Database) on 3,591 patients were recorded including ESA dose (UI/kg/week), erythropoietin resistance index (ERI) [U.I weekly/kg/gr hemoglobin (Hb)] and hospitalizations. Moreover the cumulative Fe dose (mg/kg of bodyweight) administered over the last 2 years was calculated. Univariate and multivariate analyses were performed to identify the main predictors of ESA resistance and risk of hospitalization. Patients belonging to the 4th quartile of ERI were defined as hypo-responders. The 2-year iron cumulative dose was significantly higher in the 4th quartile of ERI. In hypo-responders, 2-year cumulative iron dose was the only iron marker associated with ESA resistance. At case-mix adjusted multivariate analysis, 2-year iron cumulative dose was an independent predictor of hospitalization risk. In ESA-treated patients cumulative Fe dose could be a useful tool to monitor the appropriateness of Fe therapy and to prevent iron overload. To establish whether the associations between cumulative iron dose, ERI and hospitalization risk are causal or attributable to selection bias by indication, clinical trials are necessary.

Over-exploitation and pollution have been identified as the main problems facing the Silao-Romita aquifer in Guanajuato, Mexico. The objective of this paper is to analyze the current situation, characterized by a clear lack of legislative enforcement, dispersion of competences, and scarcity of economic resources, in order to establish a new prioritization of action plans, and choose from among three specific management options. One of the main challenges when addressing these problems in a holistic manner is the conflicting viewpoints of the sectors involved. As each stakeholder has a different perception, there is a clear need for appropriate mechanisms to reach a consensus in decision-making. To achieve the objective, we use the Analytic Hierarchy Process (AHP), because of its flexibility and the availability of mathematical axiomatic principles and techniques to obtain group preferences and priorities. In addition, we use several tools developed by the authors to obtain consistency, streamline the trade-off between stakeholder know-how and synthetic consistency, and consistently complete partial judgments given by some of the stakeholders. The problem of obtaining a consensus among the actors involved regarding criteria and alternatives is also considered. The obtained results are intended to serve as guidelines for conducting priority actions to help solve the general problem of the study area, and to identify the management model that best meets the needs of the aquifer, according to the actors involved. (C) 2013 Elsevier Ltd. All rights reserved., This work has been supported by project IDAWAS, DPI2009-11591 of the Spanish Ministry of Science and Innovation; with supplementary support from ACOMP/2011/188 of the education department of the Generalitat Valenciana. The first author wishes to thank CONACYT for the 10007-2011-01 scholarship program. The use of English in this paper was revised by John Rawlins.

[EN] This paper proposes a multiple kernel regression (MKr) to predict water demand in the presence of a continuous source of infor- mation. MKr extends the simple support vector regression (SVR) to a combination of kernels from as many distinct types as kinds of input data are available. In addition, two on-line learning methods to obtain real time predictions as new data arrives to the system are tested by a real-world case study. The accuracy and computational efficiency of the results indicate that our proposal is a suitable tool for making adequate management decisions in the smart cities environment., This work has been supported by project IDAWAS, DPI2009- 11591, of the Direccion General de Investigacion of the Ministerio de Ciencia e Innovacion of Spain, and ACOMP/ 2011/ 188 of the Conselleria d'Educacio of the Generalitat Valenciana.